A 75 hp, 460V, three-phase motor is controlled by a motor starter. The motor nameplate indicates a full-load current (FLA) of 96A. According to NEC 430.90, what is the required location for the motor controller disconnecting means relative to the controller?
- AWithin sight from the controller, or capable of being locked in the open position.
- BAt the branch-circuit overcurrent device location.
- CAdjacent to the motor controller, but not necessarily within sight.
- DWithin sight from the motor and the driven machinery.
Show answer & explanationAnswer & explanation
Correct answer: A. Within sight from the controller, or capable of being locked in the open position.
NEC 430.102(A) states that a disconnecting means shall be located in sight from the controller location. NEC 430.102(B) states that the disconnecting means shall be located in sight from the motor and the driven machinery. However, the requirement of being 'within sight from the motor and the driven machinery' applies to the motor disconnecting means, not necessarily the controller disconnecting means. The primary rule for the controller disconnecting means is found in 430.102(A), which requires it to be within sight from the controller location, or capable of being locked in the open position. Option B best reflects the rule for the controller disconnect. Note: The question specifically asks about the 'motor controller disconnecting means' and its location relative to the 'controller'.
Why the other options are wrong
- B. While the branch-circuit OCPD can serve as the disconnect, its location is not the primary determinant for the controller disconnect's visibility or lockability.
- C. This is incorrect; 'within sight' or 'lockable' are the key requirements, not just 'adjacent'.
- D. This describes the requirement for the motor disconnecting means (430.102(B)), not specifically the controller disconnecting means, although often they are the same device.
Motor Controller Disconnecting Means Location
NEC 430.102 mandates specific location requirements for the motor controller disconnecting means to ensure safety during maintenance and repair, primarily requiring it to be within sight of the controller or capable of being locked in the open position.
- The disconnecting means must be within sight from the controller location.
- Alternatively, it can be out of sight if it is capable of being locked in the open position.
- This ensures that personnel working on the controller can safely de-energize it.
Memory trick: See the disconnect, or Lock it, so no one gets shocked.